Mastodon Relay Subscribers List: How to View as an Admin

As a Mastodon instance admin, you manage the relay that your server uses to exchange public posts with other instances. A relay distributes your local public posts to all subscribed instances and brings their public posts into your federated timeline. Without a clear view of who subscribes to your relay, you cannot audit federation partners or troubleshoot delivery issues. This article explains how to find the relay subscribers list using the Mastodon admin interface and the Sidekiq dashboard, and what to do if the list appears empty or incomplete.

Why Mastodon Does Not Show a Direct Subscriber List

Mastodon relays work on a push-pull model. When you enable a relay, your instance sends a subscription request to the relay server. The relay server then pushes public posts from all subscribed instances to your instance. The relay server itself decides which instances receive those posts — Mastodon does not maintain a local database of which remote instances subscribe to the relay that your instance uses.

The Mastodon admin interface only shows relays that your instance has subscribed to, not the reverse. This design is intentional to keep relay operations lightweight. To see who subscribes to your relay, you must check the relay server’s own subscriber list or examine inbound subscription requests that your Mastodon instance receives from other instances.

What the Admin Relays Page Actually Shows

In the Mastodon admin panel, navigate to Administration > Relays. This page displays a table with columns for the relay URL, the current status (enabled or disabled), and the last successful delivery time. There is no column for subscriber count or subscriber domains.

Where Inbound Subscription Requests Appear

When a remote Mastodon instance subscribes to the same relay as your instance, the relay server sends a subscription confirmation to your instance. Mastodon processes this via background Sidekiq jobs. If the job succeeds, the remote instance is added to your instance’s internal list of relay subscribers — but this list is not exposed in the admin UI. You can only see these jobs in Sidekiq’s web interface.

Steps to View Relay Subscribers via Sidekiq

1. Open the Sidekiq dashboard
   Append /sidekiq to your Mastodon instance URL. For example, if your instance is https://mastodon.example.com, visit https://mastodon.example.com/sidekiq. You must be logged in as an admin to access this page.
2. Click the Busy or Retries tab
   Relay subscription jobs are named Pubsubhubbub::SubscribeWorker or ActivityPub::DeliveryWorker. Look for jobs with arguments that contain a relay URL or a remote instance domain.
3. Click on a job to view its arguments
   Each job contains a JSON payload. The subscriber field shows the remote instance’s domain. The relay_url field shows the relay server address. Copy the remote instance domain from this field.
4. Check the Scheduled tab for pending subscriptions
   If a remote instance subscribed but the job is scheduled for later retry, you can still see its domain in the job arguments. This indicates a temporary delivery issue.
5. Export the subscriber list manually
   Copy all unique remote instance domains from the job arguments into a text file. This file serves as your subscriber list.

Alternative Method: Check the Relay Server’s Subscriber Endpoint

Most Mastodon relays are powered by the pubsubhubbub protocol. The relay server exposes a subscriber list at a well-known URL. This method works only if you control the relay server or if the relay provides a public subscriber endpoint.

1. Find the relay server’s base URL
   Go to Administration > Relays and note the relay URL. For example, https://relay.example.com.
2. Append the subscriber path
   Most relay servers expose subscribers at /subscribers or /api/v1/subscribers. Try https://relay.example.com/subscribers.
3. Authenticate if required
   Some relays require an API token. Check your relay’s documentation. If the relay is public, the list may be accessible without authentication.
4. Parse the JSON response
   The response is typically a JSON array of objects with a callback or subscriber field containing the remote instance domain.

Common Issues When Viewing Relay Subscribers

Sidekiq Shows No Pubsubhubbub Jobs

If your instance has been running for a long time, old subscription jobs may have been automatically deleted from Sidekiq’s history. Mastodon’s default job retention is 7 days. To see older subscriptions, you must check the Mastodon production log file.

SSH into your server and run: grep "pubsubhubbub" /home/mastodon/live/log/production.log | grep "subscribe". This returns all subscription events with timestamps and remote instance domains.

Relay Server Returns 403 or Empty Response

Many relay operators restrict access to the subscriber list for privacy reasons. If you get a 403 error, contact the relay operator and ask for a subscriber list export. Some relays provide a paid tier that includes subscriber analytics.

Subscriber Count Does Not Match Expected Number

A relay subscriber list is a snapshot in time. Instances may unsubscribe at any time. If your list shows fewer subscribers than expected, check the relay server’s uptime and whether your instance is still receiving deliveries from the relay. Go to Administration > Relays and look at the Last delivery at column. If deliveries stopped, the relay may have dropped your instance.

Mastodon Relay Subscriber Sources Compared

Item	Sidekiq Job Arguments	Relay Server Endpoint	Production Log File
Data freshness	Last 7 days only	Real-time	Since log rotation
Requires SSH access	No	No	Yes
Shows pending subscriptions	Yes	No	Yes
Privacy compliance	Instance domain only	Instance domain only	Instance domain only

You can now view the list of instances that subscribe to your Mastodon relay by checking Sidekiq job arguments or the relay server’s subscriber endpoint. For a complete historical record, grep the production log file. If you need to audit federation partners regularly, consider setting up a cron job that extracts subscriber domains from the log file and saves them to a CSV. This gives you a permanent audit trail without relying on Sidekiq’s limited retention.